Patent Application
20080101002
1. Field of the Invention
Embodiments of the present invention relate to a plasma display device. More particularly, embodiments of the present invention relate to a plasma display device having a sealing member to prevent an electrical opening or short of electrode terminals thereof.
2. Description of the Related Art
In general, a plasma display device may include a plasma display panel (PDP), a chassis base that supports the PDP, and a plurality of printed circuit board assemblies (PBAs). The PDP may display images by generating red (R), green (G), and/or blue (B) light via a gas discharge phenomenon, i.e., triggering vacuum ultra-violet (VUV) light in plasma discharge gas, thereby exciting a photoluminescent material to emit visible light. The gas discharge phenomenon may be triggered by application of voltage to the discharge gas via electrodes controlled by the PBAs.
Each of the PBAs of the conventional plasma display device may control a corresponding set of electrodes, i.e., sustain electrodes, scan electrodes, and/or address electrodes, and may be connected thereto through a flexible printed circuit (FPC) and a connector, e.g., an anisotropic conductive film (ACF). For example, an address buffer board may control a plurality of address electrodes positioned on a rear substrate of the PDP, and may be connected to terminals of the address electrodes via the FPC. The electrodes of the PDP may be fabricated of a photosensitive silver through, e.g., printing, drying, light exposure, development, and/or baking.
However, in addition to exhibiting high electrical conductivity, silver may exhibit self-diffusion and migration characteristics. In other words, silver may interact with, e.g., moisture in the air, and become ionized, thereby causing openings and/or electrical shorts of the electrode terminals. Open and/or shorted electrode terminals may cause line defects in the PDP. For example, when terminals of the address electrodes are exposed to external atmospheric conditions, i.e., moisture, oxygen, organic/inorganic impurities, and so forth, the PDP may have defects in vertical lines thereof, i.e., a vertical line defect. Such lines defects may cause PDP discharge defects, brightness deterioration, inferior driving properties, and an overall reduced lifespan of the PDP.
Attempts have been made to seal a connection area between the electrode terminals and the FPC in order to minimize exposure of the electrode terminals to external atmospheric conditions. However the conventional sealing material may exhibit low adherence characteristics and a high water-vapor transmission rate, thereby causing corrosion and/or oxidation resulting in electrical openings or shorts. Accordingly, there exists a need for an improved sealing material to minimize contact between the electrode terminals and the external atmosphere.
Embodiments are therefore directed to a plasma display device, which substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art.
It is therefore a feature of an embodiment of the present invention to provide a plasma display device with a sealing member having improved adherence and sealing properties.
At least one of the above and other features of the present invention may be realized providing a plasma display device, including a plasma display panel (PDP) having electrodes between front and rear substrates, a chassis base on the PDP, printed circuit board assemblies (PBAs) on the chassis base, a flexible printed circuit (FPC) connecting the PBAs to the electrodes of the PDP, an anisotropic conductive film between terminals of the electrodes and a terminal of the FPC, and a sealing member surrounding the terminals of the electrodes and the terminal of the FPC, the sealing member including a surface hydrophobic modifying layer and an insulation layer.
The surface hydrophobic modifying layer may include a polysiloxane-based resin. The polysiloxane-based resin may include a siloxane resin, an alkyl silicate, or a combination thereof. The alkyl silicate may include one or more of C1 to C8 alkyl groups. The alkyl silicate may be one or more of methyl silicate, ethyl silicate, propyl silicate, isopropyl silicate, butyl silicate, and/or isobutyl silicate. The insulation layer may include one or more of a silicone resin, an epoxy resin, a styrene resin, a phenol resin, and/or a urethane resin.
The insulation layer and the surface hydrophobic modifying layer may be two discrete layers. The insulation layer may be between the surface hydrophobic modifying layer and the electrode terminals. The surface hydrophobic modifying layer may be between the insulation layer and the electrode terminals. The sealing member may have a single layer structure and the and the single layer may include a mixture of an hydrophobic material and an insulating material. The sealing member may exhibit a water-vapor transmission rate of about 30 to 50 g/cm2 per day. The sealing member may exhibit adhesion strength of about 5.0 to 5.7 MPa.
The sealing member may include a first sealing portion in contact with the terminal of the FPC and with the front substrate, and a second sealing portion in contact with the terminals of the electrodes, the terminal of the FPC, and the rear substrate. The first and second sealing portions may have a diagonal structure. The sealing member may be in direct contact with the terminals of the electrodes and the FPC.
At least one of the above and other features of the present invention may be further realized providing a method of manufacturing a plasma display device, including attaching a chassis base on a plasma display panel (PDP), the PDP having electrodes between front and rear substrates, mounting a printed circuit board assembly (PBA) on the chassis base, electrically connecting the PBA to the electrodes of the PDP via a flexible printed circuit (FPC), such that an anisotropic conductive film is formed between terminals of the electrodes and a terminal of the FPC, and forming a sealing member of a surface hydrophobic modifying layer and an insulation layer, such that the terminals of the electrodes and the FPC are enclosed by the sealing member.
Forming the sealing member may include forming the insulation layer between the surface hydrophobic modifying layer and the terminals of the electrodes. Forming the sealing member may include forming the surface hydrophobic modifying layer between the insulation layer and the terminals of the electrodes. Forming the sealing member may include applying the insulation layer and the surface hydrophobic modifying layer simultaneously on the terminals of the electrodes. Forming the sealing member may include curing the surface hydrophobic modifying layer and the insulation layer by heat-curing or UV curing. Forming the sealing member may include forming the surface hydrophobic modifying layer of one or more of a siloxane resin, an alkyl silicate, or a combination thereof.
The above and other features and advantages of embodiments of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:
Korean Patent Application No. 10-2006-0106682, filed on Oct. 31, 2006, in the Korean Intellectual Property Office and entitled: “Plasma Display Device,” is incorporated by reference herein in its entirety.
Embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are illustrated. Aspects of the invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
In the figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being “under” another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout.
An exemplary embodiment of a plasma display device according the present invention will be described in more detail below with reference to
As illustrated in
The PDP 11 of the plasma display device may include front and rear substrates 111 and 211, respectively, formed of, e.g., glass, and integrally bonded to each other by means of a sealant (not shown). Discharge cells (not shown) filled with a discharge gas may be formed between the front and rear substrates 111 and 211 to facilitate visible light emission upon plasma generation. In particular, the PDP 11 may include discharge electrodes (not shown), i.e., sustain and scan electrodes, and address electrodes 12 to trigger discharge in the discharge cells. The electrodes of the PDP 11 may be formed of, e.g., silver. The PDP 11 may use the gas discharge to display images, e.g., increased discharge sustain time may increase brightness of the PDP 1. The PDP 11 may be any suitable PDP.
The heat dissipation sheets 13 of the plasma display device may be attached to a rear surface of the PDP 11, i.e., a surface facing away from the a displayed image, to diffuse heat generated by the gas discharge of the PDP 11, e.g., during increased sustain discharge time. The heat dissipation sheets 13 may be made of a heat dissipation material, e.g., acryl-based material, graphite-based material, metal-based material, carbon nanotubes, and so forth, and may diffuse the generated heat along the xy-plane, as illustrated in
The chassis base 15 of the plasma display device may be attached to the rear surface of the PDP 11, so the heat dissipation sheets 13 may be interposed between the PDP 11 and the chassis base 15, as illustrated in
The PBAs 17 of the plasma display device may be mounted on the rear surface of the chassis base 15, and may be electrically connected to the PDP 11 to facilitate driving thereof. As illustrated in
Each of the PBAs 17 may be connected to a respective electrode set via, e.g., a flexible printed circuit (FPC) and a connector. For example, as illustrated in
As illustrated in
The sealing member 23 may be formed of a surface hydrophobic modifying layer and of an insulation layer, as will be discussed in more detail below with respect to
To be specific, the first sealing portion 23a may seal a lower end of a dielectric layer 21 covering the address electrode 12, a portion of the address electrode facing the front substrate 111, and an upper portion of the anisotropic conductive film 29. Accordingly, portions of the address electrode 12 not covered by the dielectric layer 21 and the anisotropic conductive film 29 may be sealed by the first sealing portion 23a. The second sealing member 23b may seal lower portions of the address electrode 12 and anisotropic conductive film 29, so the electrode terminals 112 exposed between the rear substrate 211 and the FPC 27 may be sealed. In other words, the sealing member 23 may completely seal the connection between the FPC 27 and the electrode terminals 112 of the address electrodes 12 from external atmospheric conditions, so that electrode terminals 112 formed of silver may be prevented from being opened or shorted due to migration or self-diffusion of the silver.
As illustrated in
The surface hydrophobic modifying layer 233a may be formed of a hydrophobic material, e.g., a polysiloxane. More specifically, the surface hydrophobic modifying layer 233a may include a dispersion of one or more of siloxane resin and/or an alkyl silicate in a solvent. The alkyl silicate may include a C1 to C8 alkyl group, e.g., at least one of methyl silicate, ethyl silicate, propyl silicate, isopropyl silicate, butyl silicate, isobutyl silicate, and/or a combination thereof. The solvent may include an alcohol, e.g., ethanol, propanol, isopropanol, butanol, and so forth, an ether, e.g., ethylene-glycol monoethylether, and/or an ester, e.g., ethyleneglycol monoethylether acetate, 3-methoxybutyl acetate, and so forth. One or more of the siloxane resin and/or the alkyl silicate may be dispersed in the solvent, and may be applied to the electrode terminals 112 by a wet coating method, e.g., printing and/or spray coating, followed by drying to form the surface hydrophobic modifying layer 233a on the electrode terminals 112.
The insulation layer 234a may include one or more of a silicone resin, an epoxy resin, a styrene resin, a phenol resin, and/or a urethane resin. The insulation layer 234a may be wet-coated on the dried surface hydrophobic modifying layer 233a, dried, and solidified, e.g., cured by thermal treatment or ultraviolet (UV) solidification, to finalize formation of the sealing member 23. If thermal solidification is performed, a temperature of about 25° C. to about 400° C. may be used.
Alternatively, as illustrated in
In yet another alternative, as illustrated in
The sealing members 23, 23′, and 23″ according to embodiments of the present invention may have a water-vapor transmission rate of about 30 to about 50 g/cm2 per day and an adhesion strength of about 5.0 to about 5.7 MPa.
Accordingly, incorporating the sealing member according to embodiments of the present invention into a plasma display device may be advantageous in preventing or substantially minimizing penetration of external moisture, oxygen, and/or other impurities into the plasma display device. The sealing member may substantially minimize migration of silver between adjacent electrode terminals, and may exhibit enhanced stability at high temperatures. Accordingly, the sealing member according to embodiments of the present invention may substantially reduce shrinkage or expansion of electrode terminals as a result of external environmental changes, thereby preventing electrical openings or shorts of electrode terminals.
Three samples of sealing members were prepared according to embodiments of the present invention, i.e., Examples 1-3. Examples 1-3 were compared to Comparative Examples 1-2 in terms of adhesion strengths at different conditions and water-vapor transmission rate. The physical sizes, shapes, and composition of the substrates in Examples 1-3 and Comparative Examples 1-2 were identical. The physical sizes and shapes of the sealing members in Examples 1-3 and Comparative Examples 1-2 were identical. Also, the silicone resin used in Examples 1-3 and Comparative Examples 1-2 was identical. Preparations of all compositions and application thereof to respective substrates were performed at standard temperature and humidity unless indicated otherwise.
an ethyl silicate solution (40 w/v (%) of ethanol dispersion) was coated on a substrate and dried. A layer of silicone resin was coated on the dried ethyl silicate layer and heat-cured at 45° C. to form a sealing member.
a silicone resin was coated on a substrate and dried. An ethyl silicate solution (40 w/v (%) of ethanol dispersion) was coated on the dried silicone resin layer and heat-cured at 40° C. to form a sealing member.
ethyl silicate and a silicone resin were mixed at a weight ratio of 1:1 in ethanol to prepare a solution. The prepared solution was coated on a substrate, dried, and heat-cured at 40° C. to form a sealing member.
a silicone resin was coated on a substrate, dried, and cured by UV to form a sealing member.
a silicone resin was coated on a substrate and dried to form a sealing member. The silicone resin layer was only dried and not solidified.
Adhesion strength of each of the sealing members prepared according to Examples 1-3 and Comparative Examples 1-2 was measured using an Instron 6022 tensile measuring device (500 g load and 90° peel-off). An edge of each of the sealing members was exfoliated from the substrate using a polyimide (PI) T-joint, and the exfoliated edge of the sealing member was pulled apart from the substrate at a speed of 5 mm/min at a normal state load. The maximum force required to pull the sealing member completely apart from the substrate was recorded. The results are presented in Table 1 below. Referring to Table 1 below, the sealing members of Examples 1-3 showed higher adhesion strength, as compared to Comparative Examples 2-3.
Water-vapor transmission rate of each of the sealing members was determined as follows. An initial weight of each sample was determined. Next, each sample was immersed in tap water and maintained therein at a temperature of 40° C. for 24 hours. After 24 hours, a weight of each sample was measured and compared to the initial weight of each sample. A weight difference after 24 hours of immersion in water of each sample was reported. The measurement results are presented in Table 2 below. As illustrated in Table 2, the sealing members of Examples 1-3 exhibited lower water-vapor transmission rates, i.e., lower water absorption, as compared to Comparative Examples 1-2, thereby signifying that moisture penetration was substantially reduced by the sealing members of Examples 1-3.
Adhesion strength of each sealing members of Examples 1-3 and Comparative Examples 1-2 was also determined under high temperature and high humidity conditions. More specifically, each sealing member was placed in a sealed chamber at 50° C. and 90% relative humidity for 5 days. Adhesion strength before and after placement in the sealed chamber was determined with the Instron 6022 tensile measuring device (500 g load and 90° peel-off) as described above. The results are shown in Table 3 below.
Referring to Table 3, the sealing members of Examples 1-3 showed little or negligible change in adhesion strength as a result of high temperature and humidity conditions, thus producing highly reliable data. On the other hand, the sealing members of Comparative Examples 1-2 showed a relatively large change in adhesion strength, i.e., respective strength decrease of 18.75% and 25%. The results signify that the sealing effect of the sealing members of Comparative Examples 1-2 may substantially deteriorate at high temperature/humidity conditions.
As described above, the sealing member including the surface hydrophobic modifying layer that includes a polysiloxane-based resin may prevent electrical openings or shorts of electrode terminals.
Exemplary embodiments of the present invention have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0106682 | Oct 2006 | KR | national |
